1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.android.server.location;
18
19import android.content.Context;
20import android.net.Proxy;
21import android.net.http.AndroidHttpClient;
22import android.text.TextUtils;
23import android.util.Log;
24
25import org.apache.http.HttpEntity;
26import org.apache.http.HttpHost;
27import org.apache.http.HttpResponse;
28import org.apache.http.StatusLine;
29import org.apache.http.client.methods.HttpGet;
30import org.apache.http.client.methods.HttpUriRequest;
31import org.apache.http.conn.params.ConnRouteParams;
32
33import java.io.DataInputStream;
34import java.io.IOException;
35import java.util.Properties;
36import java.util.Random;
37
38/**
39 * A class for downloading GPS XTRA data.
40 *
41 * {@hide}
42 */
43public class GpsXtraDownloader {
44
45    private static final String TAG = "GpsXtraDownloader";
46    private static final boolean DEBUG = Log.isLoggable(TAG, Log.DEBUG);
47    private static final String DEFAULT_USER_AGENT = "Android";
48
49    private final Context mContext;
50    private final String[] mXtraServers;
51    // to load balance our server requests
52    private int mNextServerIndex;
53    private final String mUserAgent;
54
55    GpsXtraDownloader(Context context, Properties properties) {
56        mContext = context;
57
58        // read XTRA servers from the Properties object
59        int count = 0;
60        String server1 = properties.getProperty("XTRA_SERVER_1");
61        String server2 = properties.getProperty("XTRA_SERVER_2");
62        String server3 = properties.getProperty("XTRA_SERVER_3");
63        if (server1 != null) count++;
64        if (server2 != null) count++;
65        if (server3 != null) count++;
66
67        // Set User Agent from properties, if possible.
68        String agent = properties.getProperty("XTRA_USER_AGENT");
69        if (TextUtils.isEmpty(agent)) {
70            mUserAgent = DEFAULT_USER_AGENT;
71        } else {
72            mUserAgent = agent;
73        }
74
75        if (count == 0) {
76            Log.e(TAG, "No XTRA servers were specified in the GPS configuration");
77            mXtraServers = null;
78            return;
79        } else {
80            mXtraServers = new String[count];
81            count = 0;
82            if (server1 != null) mXtraServers[count++] = server1;
83            if (server2 != null) mXtraServers[count++] = server2;
84            if (server3 != null) mXtraServers[count++] = server3;
85
86            // randomize first server
87            Random random = new Random();
88            mNextServerIndex = random.nextInt(count);
89        }
90    }
91
92    byte[] downloadXtraData() {
93        String proxyHost = Proxy.getHost(mContext);
94        int proxyPort = Proxy.getPort(mContext);
95        boolean useProxy = (proxyHost != null && proxyPort != -1);
96        byte[] result = null;
97        int startIndex = mNextServerIndex;
98
99        if (mXtraServers == null) {
100            return null;
101        }
102
103        // load balance our requests among the available servers
104        while (result == null) {
105            result = doDownload(mXtraServers[mNextServerIndex], useProxy, proxyHost, proxyPort);
106
107            // increment mNextServerIndex and wrap around if necessary
108            mNextServerIndex++;
109            if (mNextServerIndex == mXtraServers.length) {
110                mNextServerIndex = 0;
111            }
112            // break if we have tried all the servers
113            if (mNextServerIndex == startIndex) break;
114        }
115
116        return result;
117    }
118
119    protected byte[] doDownload(String url, boolean isProxySet,
120            String proxyHost, int proxyPort) {
121        if (DEBUG) Log.d(TAG, "Downloading XTRA data from " + url);
122
123        AndroidHttpClient client = null;
124        try {
125            if (DEBUG) Log.d(TAG, "XTRA user agent: " + mUserAgent);
126            client = AndroidHttpClient.newInstance(mUserAgent);
127            HttpUriRequest req = new HttpGet(url);
128
129            if (isProxySet) {
130                HttpHost proxy = new HttpHost(proxyHost, proxyPort);
131                ConnRouteParams.setDefaultProxy(req.getParams(), proxy);
132            }
133
134            req.addHeader(
135                    "Accept",
136                    "*/*, application/vnd.wap.mms-message, application/vnd.wap.sic");
137
138            req.addHeader(
139                    "x-wap-profile",
140                    "http://www.openmobilealliance.org/tech/profiles/UAPROF/ccppschema-20021212#");
141
142            HttpResponse response = client.execute(req);
143            StatusLine status = response.getStatusLine();
144            if (status.getStatusCode() != 200) { // HTTP 200 is success.
145                if (DEBUG) Log.d(TAG, "HTTP error: " + status.getReasonPhrase());
146                return null;
147            }
148
149            HttpEntity entity = response.getEntity();
150            byte[] body = null;
151            if (entity != null) {
152                try {
153                    if (entity.getContentLength() > 0) {
154                        body = new byte[(int) entity.getContentLength()];
155                        DataInputStream dis = new DataInputStream(entity.getContent());
156                        try {
157                            dis.readFully(body);
158                        } finally {
159                            try {
160                                dis.close();
161                            } catch (IOException e) {
162                                Log.e(TAG, "Unexpected IOException.", e);
163                            }
164                        }
165                    }
166                } finally {
167                    if (entity != null) {
168                        entity.consumeContent();
169                    }
170                }
171            }
172            return body;
173        } catch (Exception e) {
174            if (DEBUG) Log.d(TAG, "error " + e);
175        } finally {
176            if (client != null) {
177                client.close();
178            }
179        }
180        return null;
181    }
182
183}
184